Human eyes are horizontally separated by a distance of about 65 mm, and the binocular disparity caused by this horizontal separation is the most important factor in 3-dimensional perception. That is, the left and right eyes see different two-dimensional images. When the images are transmitted to the brain through the retinas, the brain precisely combines the images with each other, thus realizing the depth and reality of an original 3-dimensional image.
Up to date, there have been attempts to realize 3-dimensional shapes through various types of devices such as optical instruments, and some technologies have reached commercialization. For example, a polarizing filter method is technology for separating images acquired with the left and right eyes using a shielding effect obtained by the combination of orthogonal polarizing devices, and is implemented such that the left and right images are protected on a screen through a video projector equipped with orthogonal polarizing filters or the like, and are observed using glasses equipped with orthogonal polarizing filters or the like. In addition to the polarizing filter method, there is a time division stereoscopic representation method of alternately and sequentially switching left and right images, having a parallax difference therebetween, presenting the left and right images to both eyes, and representing the left and right images as a 3-dimensional image using shutter glasses switched in synchronization with the switching operation of left and right images. Moreover, there are glasses-free methods requiring no special glasses, such as a parallax barrier method, a lenticular method, and a holography method. The parallax barrier method is implemented such that images corresponding to left and right eyes are alternately arranged behind a thin slit-shaped opening called a parallax barrier and are spaced apart from the parallax barrier by a suitable distance, so that they can thus be precisely separated and viewed as a 3-dimensional image when the left and right images are viewed through the opening at a specific time point. The lenticular method is implemented such that left and right images are arranged on the focal surface of a semi-cylindrical lens, called a lenticular screen, in stripes, are separated depending on the directivity of a lenticular lens plate, and are thus represented as a 3-dimensional image without requiring glasses when the images are observed through the lenticular lens plate. In addition to the above-described methods, many attempts to satisfactorily obtain a 3-dimensional image have been made to date. However, these conventional methods are problematic in that special devices, such as polarizing glasses or a lenticular lens, are required, or in that the construction of a device for obtaining a 3-dimensional image is very complicated. Accordingly, the conventional methods are problematic in that, since the costs of manufacturing the device are very high, general consumers cannot easily access such methods.
Korean Patent No. 423124, entitled “Three-Dimensional Image System” and filed by the present applicant with the Office of Patent Administration on Jun. 20, 2001, is intended to obtain such a 3-dimensional image more simply and excellently. That is, the patent, incorporated with the present invention, discloses an optical recording device in which a film or the like, which is an image recording medium, is placed at a location far beyond a Fresnel region, which is a region in which light travels straight when passing through slits, thus realizing a clear 3-dimensional image without being influenced by an afterimage attributable to diffraction at the slits. FIG. 1 is a schematic diagram showing the construction of an optical device for recording a 3-dimensional image using slits, and FIG. 2 is a conceptual view showing the image formation of a 3-dimensional image recording device using a slit plate proposed by the present applicant. Unlike conventional optical devices using slits, in which 3-dimensional image information is recorded on a film, which is an image recording medium, within the range of a Fresnel region in which light, passed through slits, travels straight, the above patent is configured such that 3-dimensional image information is recorded on a film 203, which is an image recording medium, with the film 203 being located a sufficient distance from a slit plate to be far beyond the Fresnel region, thus preventing an unnecessary afterimage, attributable to the characteristics of a slit plate 204, from being recorded. That is, the optimal image formation distance between the slit plate 204 and the film 203 is determined according to the ratio of the widths of the transparent parts and the opaque parts of the slit plate. In FIG. 2, “a” denotes the length of the Fresnel region, which is the region in which light, passed through slits, travels straight, and “b” denotes an optimal image formation distance requiring that an image is formed at a location beyond the Fresnel region. Reference numeral 201, which is not described, denotes the main body of the image recording device, and reference numeral 202 denotes a lens. technology applicable to analog optical instruments, such as analog cameras or camcorders, but, recently, digital image recording devices have prevailed.
FIG. 3 is a longitudinal sectional view of a conventional Charge Coupled Device (CCD). A CCD 300 includes a main body 301, having an open top and a cavity formed therein, and having a plurality of chip pins 303 formed on the outer surface thereof, a light receiving element 302 composed of a plurality of pixels and mounted on the bottom surface of the interior of the main body, and a transparent glass plate 304 for covering the opening of the cavity of the main body 301. Such a CCD is adapted to accumulate charges corresponding to image information of light in the light receiving element, which sensitively reacts to the brightness of image light passed through a lens, and to record and store the charges in an external memory device or the like. Most digital image recording devices have recently adopted the CCD. However, it is impossible to obtain a 3-dimensional image using only the conventional CCD 300 itself, and it is only possible to record the brightness of light, passed through the lens, and thus the support of a separate device or separate software to the obtainment of a 3-dimensional image is required.